Updated · Methodology: named formula library
Home Energy Audit Calculator
Estimate home energy usage and savings opportunities.
Value A to Value B = 4:1 (4 as decimal).
Why This Calculation Matters
The Home Energy Audit Calculator helps you screen a efficiency investment before spending serious money on a formal quote. It captures the core economics; to finalize a decision, combine these numbers with installer-specific proposals, tax credits, and utility rate plans.
How to Use This Calculator
- Enter your values in the input fields, each one has a label and help text explaining what to type.
- Results appear instantly as you type; there's no "calculate" button to press.
- Change any input to compare scenarios side by side.
All math happens in your browser. Nothing you type is sent to a server, saved, or shared.
Beyond the Calculator
Real-world performance depends on local climate, shading, equipment efficiency, and rate structure. Use this number as a screen, then get 2-3 installer quotes for the definitive answer.
How to Use the Home Energy Audit Calculator
Enter the required values in the input fields on the left. Results update instantly on the right as you adjust your inputs.
Understanding Your Results
Review each output value and its description to understand how your inputs affect the outcome. Adjust values to compare different scenarios.
Tips
- All calculations happen in your browser, your data is never stored
- Bookmark this page for quick access
- Try different values to see how results change
Formula
Cost = kWh × rate. kWh = watts × hours ÷ 1000. National average U.S. residential rate is ~$0.16/kWh (2025), but ranges from ~$0.11 (WA) to ~$0.44 (HI).
Worked Example
100 Value A to 25 Value B
- a
- 100
- b
- 25
- Result
- 4:1 (4.00)
100 / 25 = 4.00. Simplified: 4:1.
When to Use This Calculator
- Screen a solar, battery, or EV investment for payback period.
- Model what-if scenarios as utility rates, tax credits, or panel costs change.
- Compare vendor proposals on a consistent basis.
Limitations & Common Mistakes
- Actual system output depends on shading, panel orientation, local weather, and equipment losses.
- Tax credits and utility rate plans change, verify with your installer and utility provider.
- Payback calculations ignore financing costs and opportunity cost of capital.
Frequently Asked Questions
How is the Home Energy Audit Calculator computed?
Value A divided by Value B, plus a simplified ratio (e.g., 4:3) using greatest common divisor. Both decimal and ratio forms are useful in different contexts: decimal for math, ratio form for comparisons or recipe scaling.
What does Value A:Value B mean?
It's a comparison: for every Value B unit, you have a corresponding amount of Value A. Useful when the absolute numbers matter less than the proportion (e.g., reading 8:1 LTV/CAC immediately tells you the unit economics are healthy without needing the dollar amounts).
Why simplify the ratio?
4:3 is more readable than 200:150. The simplified form (using greatest common divisor) preserves the proportion while making it easier to interpret. Common simplified ratios: 16:9 (widescreen), 4:3 (legacy displays), 3:1 (LTV:CAC for SaaS).
When is a ratio more useful than the absolute values?
Comparison across scales. A $1B company and a $1M company can both have a 3:1 LTV:CAC; the ratio reveals comparable unit economics regardless of scale. Use ratios for benchmarking; use absolute numbers for budgeting.
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Source: BLS Consumer Price Index, 2026.